Rotating field-magnet.



B. a LJUNGSTRM.

ROTATING FIELD MAGNET.

APPLICATION mso MN. x9. |918.

l ,273,385i Patented July 23, 1918.

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LIDINeN, six/EDEN.

ROTATING FIELD-MAGNET.

Application filed January 19, 1918.

'o all lui/tom t may concern.'

Be it known that we, Bracci). LJuNGsrnM, director, and Fnuoniir LJUNAGSTRM, chief engineer, subjects of the King of Sweden, residing at N arvavgen 21, Stockholm, Sweden, and Brevik, Lidingn, Sweden, have invented certain new and useful Improvements in Rotating Field-Magnets, of which the following' is a specification.

The present invention relates to rotating field-magnets and consists chiefly in the slots of the field-magnet being provided with a groove at each side of the bottom, into which the side insulations may enter.

The invention also comprises other arrangements which will be hereinafter described in connection with some preferred embodiments of the invention.

One object of the same creep-length by means of a thin bottom insulation as may be obtained by a thicker one and, further, to increase the sectional area of the rotating field-magnet and thus to increase its capacity.

The accompanying drawing illustrates some preferred embodiments of the invention. Figure l shows a cross-section through a field-magnet with parallel slots, Fig. 2 part of a cross-section with radial slots, Figs. 3 and t cross-sections of different slots, Fig. 5 a section of a slot with an ordinary bottom insulating strip, and Figs. 6 and 7 different forme of bottom insulatino' strips according to the present invention.

1 designates the slot which is closed by a longitudinal wedge 2 serving to retain the winding Provided in the bottom of the slot are grooves A (Figs. l, 2, 3) into which the ends of the side insulations 5 enter. Preferably said grooves are given a round cross-section to prevent cracks in adjacent parts. Duc to the fact that the side insulations 5 enter into these grooves 4, the insulating plates 6 may be made relatively thin, as the electrical creep-length from the conductors in the slot to the iron close to the inner insulation of the slot is determined by the cross-sectional measures of the groove It.

By the arrangement described the same creep-length is obtained by means of the thin bottom insulation 6 3) as by the ordinary, thick insulation shown in Fig. The grooves may then be made correspondingly' shaliower whereby the cross-section of the rotating ieid magnet will be iargeri Speciication of Letters Patent.

the invention is to obtain Patented July 23, 1918. serial No. 212,772.

Duc to this fact the area available for the magnet flux and thus also the capacity of the rotating magnet, will be increased. As a consequence the total capacity of thev electrical generator is also increased.

As shown in Figs. 4 and 7 the grooves may be made in a separate strip placed on the bottom of the slot and preferably consisting of iron. If a similar strip 8 is used beneath the wedge 2 (Fig. A), the same advantage is obtained in respect of great creeplength and thin and iiexible insulation. A thin and flexible insulation is particularly wanted with regard to the .fact that the conductors 3 are forced together by the wedge being driven into the slot. Further a relatively thick strip 8 is wanted to prevent damage of said insulation by the insertion of the wedge.

In certain cases a variation of the magnetic flux is wanted which may be effected by making one of the strips 7 and 8, Fig. 4, or both of magnetic or non-magnetic material whereby a certain adjustment of the potential and magnetization curve may be obtained without any other alteration.

Figs. 6 and 7 show some modifications of the strips 'r' and 8 shown in Fig. A the strips eing composed of magnetic material 9 and of non-magnetic material l0.

laims.

l. A rotating field-magnet provided with slots .for containing conductors and insulating linings for such slots, each slot having grooves at its sides under thc bottom part of the insulatingv lining, said grooves being arranged to allow the side walls of the insulating' lining to enter them for the purposes set forth.

2. A rotating field-magnet provided with slots for containing conductors, and insulating linings for such slots, each slot having grooves at its sides under the bottom part of the insulating lining, said grooves being arranged to 'allow the side walls of the insulating' lining to enter them and formed in a separate strip located in the bottom of the slot.

3. A rotating field-magnet provided with slotsI for containing conductors ard with insulating' lining.'I for said slots, each slot having grooves at its sides under the bottom part of the insulating lining and being closed bv a wedge, the said grooves beinetermed in separate strip located in the bottom part oi' the slot and a similai-` sti-ip slots in which Strips said grooves are formed, siinlhyrljyY gi'ooveclbeing looate'cl-unclei1tlie at least one ofso-1d strips benigpoi'tly oi weclge, the' grooves zof siicly Sti-ips being aiinxgnetio and 'partly fof non-1nagnetio'4 maranged to allow the side Walls ofthe Insutei-lala" 5 loting lining to entei1 them for theupurposheg Intestimony whereof ive affix our signaset forth. tures 1n presence of two witnessee Y 4. Arotettinglield-niagnet proyided with A BIRGER LJUNGSTR/NL slots for containing conductors, insulating FREDRIK LJUNGSTRM' linings for said slots, each Slot hzLYing 10 grooves at its sides adapted to receive lthe VVitnesSes:

sigle Wells pfgsaid inenlatingliningfs and sep-v JACOB BAGGE, aatej Stripsi aty the bottoni; and top oi said FRITZ E. HAnLiN. Gpigifefigf` this natellfnmwbgeobtanedzfw fixa:l cents each, by adsresngthf? vmmssine ofl'ftent, 

